Nosocomial infections are those which are a result of treatment in a hospital or a healthcare service unit, but secondary to the patient's original condition. The literature is replete with case reports of fomite transmission in the hospital setting. Health care providers are often cited as the mode of transmission from fomite reservoir to patient.
Gram-positive bacteria are a major cause of nosocomial infection. The most common pathogenic isolates in hospitals include Enterococcus spp., Staphylococcus aureus, coagulase-negative staphylococci, and Streptococcus pneumoniae (See, e.g., Principles and Practice of Infectious Diseases, 4th ed. Mandell G L, Bennett J E, Dolin R, ed. Churchill Livingstone, New York 1995), many strains of which are resistant to one or more antibiotics. Enterococcus spp. are part of the normal gut flora in humans. Of the more than seventeen enterococcal species, only E. faecalis and E. faecium commonly colonize and infect humans in detectable numbers (E. faecalis is isolated from approximately 80% of human infections, and E. faecium from most of the rest).
Nosocomial infections are even more alarming in the 21st century as antibiotic resistance spreads. Vancomycin-resistant enterococcus (VRE) spp. are becoming increasingly common in hospital settings. In the first half of 1999, 25.9% of entercoccal isolates from Intensive Care Units were vancomycin-resistant; an increase from 16.6% in 1996 and from 0.4% in 1989. VRE are also commonly resistant to many other commercial antibiotics, including beta-lactams and aminoglycosides. Thus, patients who are immunocompromised or those having a prolonged hospital stay are at increased risk for acquiring a VRE infection.
The problem of antibiotic resistance is not unique to Enterococcus spp. Strains of many other potentially pathogenic Gram-positive bacteria displaying antibiotic resistance have been isolated including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Staphylococcus aureus (VRSA), glycopeptide intermediate-susceptible Staphylococcus aureus (GISA), vancomycin-resistant MRSA (VR-MRSA) and penicillin-resistant Streptococcus pneumoniae (PRSP). Like VRE, therapeutic options for treating infections by these organisms are limited.
The spread and severity of nocosomial infections is due to multiple factors. Hospitals house people who are ill or infected and whose immune systems are often in a weakened state. Increased use of outpatient treatment means that people who are in the hospital are sicker on average. Medical staff move from patient to patient, providing a way for pathogens to spread. Many medical procedures bypass the body's natural protective barriers. Routine use of anti-microbial and anti-bacterial agents in hospitals creates selection pressure for the emergence of resistant strains.
For centuries it was assumed that infectious diseases were spread primarily by the airborne route or through direct patient contact, and the surrounding environment played little or no role in disease transmission. Up until 1987 the Centers for Disease Control and the American Hospital Association focused on patient diagnosis due to the belief that nosocomial infections were not related to microbial contamination of surfaces. Over the years studies have changed the perspective on infectious disease transmission to include a more complex multifactorial model of disease spread. There is now growing evidence that contaminated surfaces of inanimate objects play a key role in the spread of infectious diseases.
Concern about fomites on medical equipment is heightened when particularly virulent or resistant organisms are identified. Accordingly, there is a need for devices and methods which decrease or eliminate the risk of infectious disease transmission through inanimate objects.